Missing looping index added. Without index empty rows returned for csv column headers.
Merge pull request #3130 from dionysiosarvanitis/fix/pdo_result__list_fields

Missing looping index added.
Fix #3131
Merge branch 'develop' of github.com:EllisLab/CodeIgniter into develop
Fix a few typos and add a backport (compat) for hex2bin()
update